Linux - make sure of your cat6 cable

I have been using cat6 cable on all the new pulls of cable, but I didn't realize I had a section of cat5 cable from the second computer.  I thought it was slow, but I did an iperf test, and it showed the throughput was only 100 mbps.  I changed the cable and it's up to 1000.  Amazing.  This becomes important when you get a 4K tv.  Also, we are getting direct fiber soon, and everything should be up to the gigabit.